Electrical insulator and method of making same



W. BUSH,

m g U// UNITED STATES PATENT OFFICE.

JOHN IV. BOOH, EAST LIVERPOOL, OIIIO.

ELECTRICAL INSULATOR AND METHOD OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 600,475, dated March 8, 1898. Application filed October 28, 1897. Serial No. 656,165. (No model.)

To aZZ whom it may concern.-

Be it known that I, JOHN W. BOCH, a citizen of the United States of America, residing in East Liverpool, Ohio, have invented Improvements in Electrical Insulators and Methods of Making the Same, of which the following is a specification.

My invention consists of improvements in porcelain or earthenware insulators and in the mode of manufacturing the same.

Insulators constructed in accordance with my invention are more particularly such as are adapted for use on electric lines for the transmission of energy with currents of high voltage.

In the accompanying drawings, Figure 1 is a sectional view illustrating one step in the manufacture of my improved insulator. Fig. 2 is a sectional view of a finished insulator.

In the drawings I have shown a triple-petticoat type of insulator, but my invention may be employed in the manufacture of doublepetticoat insulators or other styles. The insulator is built up of two or more separatelymolded parts of clay. In the case of the triple-petticoat style of insulator it is preferred to make it of three separately-molded pieces of clay. The inner part A is pressed or molded with a threaded or other suitable socket a for the reception of the usual pin of iron or other suitable material, and the outer part O, shaped like an inverted bowl, is provided with a cross-notch c on the top for the reception of the electrical conductor and has side shoulders c c, by which the conductor may be wired down. The intermediate partB is made bowl-shaped, and the several parts are molded so as to nest or fit into each other in the manner shown, preferably with corresponding centering projections and recesses a; 00.

In carrying out my invention the separately-molded parts A B C after coming from the press are first dried out separately. This is preferably done in an oven or kiln in the usual manner of drying clay articles by the process known as biscuit-firing. hen these separate parts have thus been biscuitfired or otherwise dried and are ready to be put into the vitrifying-kiln, they are each coated with a glazing material, preferably all over, as by dipping the article into such liquid glazing material. The two or more parts of each insulator thus coated are now fitted into each other and are stood upside down, as it werethat is, with the lower ends of the bowls uppermost, as shown in Fig.1. Glazing material is then put into the j oints-that is, into the annular channels between the petticoatsand this may be most conveniently done by pouring the liquid glaze into the channels, as indicated at y in said figure. The parts thus put together and supplied with glazing are now put into a sagger with the petticoats uppermost, as shown in Fig. 1, and placed in a kiln,in which under great heat the clay shrinks and becomes vitrified, as usual, and the glazing material melts and becomes of a glass-like character. That glaze which was put into the annular channels between the petticoats flows down into and fills all the spaces between the parts of the insulator, such spaces either being there by lack of correct fit of the parts or arising during the shrinkage by the vitrifaction of the clay. The result is that the two or more separatelymolded parts are firmly united to each other throughout by means of the glass-like glaze.

Owing to the supply of the extra glazing material between the petticoats I or at the joints, I prevent the formation of air-spaces or cracks for the entrance of moisture in the finished insulator and which are almost certain to occur in the absence of such provision of additional glazing material. A solid and practically impenetrable layer or layers of glaze will thus be formed between the conductor and the supporting-pin intermediate between the porcelain or earthenware parts of the insulator.

I claim as my invention 1. The mode herein described of making a petticoat-insulator by molding it in two or more parts of clay, coating them with glazing material, fitting them together, supplying eX- tra glazing material at the joints between the petticoats and firing the united and coated parts with the petticoats uppermost, so that the glazing material will be melted and flow into and fill all the spaces between the parts, substantially as described.

2. The mode herein described of making a petticoat-insulator, by molding it in two or more parts of clay, fitting them together, supplying glazing material at the joints between the petticoats, and then firing with the petticoats uppermost, whereby the clay will become vitrified, and at the same operation the glazing material will be melted and flow into and fill the spaces between the parts, substantially as described.

3. The mode herein described of making a petticoat-insulator, by molding it in two or more parts of clay, biscuit-firing the parts separately, fitting them together, supplying glazing material at the joints between the etticoats, and thin g, with the petticoats uppermost, so that the glazing material will be melted and flow into and till all the spaces between the parts, substantiallyas described. 

